Blowout preventer stack design patents: mapping who holds the ram and annular sealing claims
30.3% concentration. the five leading assignees together hold 1,143 of the 3,772 records in scope, a share concentrated in a field with no shortage of single-filing entrants below them. Filings climbed to a peak of 251 in 2017, then eased off; 2021 stood at 169 before falling to 54 by 2024, a -68% move over that span. Counts from 2025 onward are still incomplete because publication typically lags filing by around 18 months, so the most recent years should not be read as a continued decline yet.
- 1HYDRIL USA MANUFACTURING LLC7.8%
- 2HYDRIL USA DISTRIBUTION LLC7.0%
- 3CAMERSON INT CORP6.1%
- 4SCHLUMBERGER TECH CORP5.4%
- 5HYDRIL CO4.0%
See the full blowout preventer stack design analysis in Eureka
- The complete ranking, not just the top five
- Every IPC branch with its share of the corpus
- The most-cited records, and where claim space is still thin
Common questions on BOP stack design patents
Who holds the most patents on blowout preventer stack design?
Filing activity in this dataset is concentrated among a small group of established oilfield equipment and service companies, with the top-ranked assignee holding 293 of the 3,772 records in scope. The next four leading assignees bring the combined top-five share to 1,143 records, or 30.3% of the field. Below the top ten, which together hold 44.0% of records, filing activity spreads across many companies with far smaller counts, so freedom-to-operate work should prioritise the leading names first.
Is patent filing for blowout preventer technology still growing?
No — filings peaked at 251 in 2017 and have declined since, with the 2021 to 2024 window showing a 68% drop from 169 to 54 records. However, publication typically lags filing by around 18 months, so 2025 and 2026 counts in any dataset are still incomplete and should not yet be read as confirming a continued decline. The safest complete-year comparison currently available ends at 2024.
What technology areas fall under blowout preventer stack design patents?
The core of this landscape sits in IPC subclass E21B (earth and rock drilling), which covers 93.5% of the 3,772 records because BOP stacks are defined by their wellbore-sealing function. Smaller but meaningful activity appears in valves and taps, fluid-pressure actuators, pipe fittings, control and regulating systems, cutting mechanisms, pumps, and digital data processing. These secondary classes mark where BOP claims intersect with hydraulics, automation and monitoring rather than pure mechanical sealing.
Disclaimer. This analysis is based on Patsnap Eureka data drawn from a limited snapshot of global patent records and is provided for general information and reference only. Patent data carries inherent limitations — recent filings are under-counted because of publication lag, counts may be on a record or family basis, classification and applicant-name data may contain errors or duplicates, and the underlying search query defines the scope shown — so the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing here is an exhaustive prior-art, novelty, freedom-to-operate or validity search, nor does it constitute legal, financial or professional advice, and it should not be relied upon as such. Verify independently and review with qualified patent and legal professionals before acting on it.
Method: Filing trend and technology composition. Derived from a Patsnap search on Blowout Preventer Stack Design covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish. Every share divides by all records in scope. Data: Patsnap Eureka. See the full landscape report.